Add cacheability metadata for [current-date] tokens

It's the "current-date" that gives the uncacheable metadata, not the formatting. While altering that based on a custom format is possible, it's tricky, because if you do [node:created:custom:s], you'd add a very low cacheablity where it's not needed because the date it depends on is actually stable and won't change unless the node is saved (which is covered by the cache tag).

Did you see https://drupal.slack.com/archives/C1BMUQ9U6/p1744824193034209, this looks very related to that discussion.

You could try to extend the cacheability and not lower it, but that's risky, because you don't know where exactly that comes from. There might be other tokens that do need a lower max age.